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## Homework Statement

What gauge pressure is required in the city mains for a stream from a fire hose connected to the city mains to reach a vertical building of height 15m?

## Homework Equations

Bernoulli Equation

## The Attempt at a Solution

I have tried this sum. My confusion is regarding choice of points where Bernoulli equation is to be applied. I assume two points,one at the bottom with height h1, P1 and v1, and the other at top of the building with h2=15m, P2=0 (as water is supposed to go this much height only) and v2=0 (again water is supposed to be stationary as this is the maximum height). I can't understand how is v1=v2, this is the condition that provides the required answer. Some of my work is given in the attached image please. I shall be grateful for the reply.